Drupal performance and bacnhmarks: maximum users, multiple front end servers, etc.

Any figures that people give you will be quite useless unless you mention the hardware and software environment that you're planning on running the site on, or the complexity of your potential site. Still, I'd be interested to hear people's opinions on how Drupal scales to these levels.

On a properly configured and optimized server environment with seperate database and web servers and heavy caching (and perhaps a seperate, light-weight web server process to serve and cache static content), I would guess that you could handle a site twice the size and bandwidth of drupal.org without running into any problems that are inherent in Drupal itself. Some contrib modules (like pathauto running on Drupal 4.6) are known to scale poorly because of the way Drupal was handling URL aliases, but the core itself should be tight enough for any site you could throw at it.

If you're truly expecting traffic of this scale, you should consider doing some more research into what you're letting yourself in for before you choose a CMS to use. I think Drupal should be able to handle the load and is flexible enough to build your site with, so I'd recommend trying it and doing some automated load testing. You will need a stable, secure, and optimized server to power this (and a few gurus to maintain it) regardless of the CMS you choose.

demolicious | leafish

Testing is the only sensible way to go about it.

How much resources are required depends roughly on how many features you enable. If you show 20 comments, currently logged in users, a random screenshot from the gallery, enable statistics etc... you will quickly only be able to serve 1/10 as many users as you would otherwise.

I am sure that myspace.com is not handled by one server, and probably craigslist isn't either. By using some clever proxy- and redirect tricks you would only be limited by the database-server (you could have as many proxys and webservers as you wanted), and that could potentially be thousands of simultaneous users. Chances are that computing power will increase sufficiently to accomodate for growth beyond this, even with a single database server.

Whatever you do, be sure to try eaccelerator or a similar package. You can gain a lot by selecting a suitable machine, preferably with more than 2Gb of fast RAM. A dual 2.8GHz machine with 533Mhz FSB can easily handle a million pages per day, probably three times that.

Here are some intresting posts from my own research on the subject.

Drupal Conference: 100% availability, scalability and security with Drupal
David 'Kat' Monosov talks about how to ensure 100% availability, handle scalability to millions of users, and ensure the security of a mission-critical Drupal setup: "In fact, we will mostly be talking about how Drupal is flexible enough to allow for known, well documented methods in network and system administration to be applied to it in order to reach the goals mentioned with (nearly) no modifications."

It's recommended to use distributed MySQL for the backend, installed on seversl servers parallel.
http://www.mysql.com/products/database/cluster

How to patch drupal to work with very big taxonomies
http://drupal.org/node/40317

Enterprise drupal: Examples of large drupal installations

10 Biggest and best drupal sites
http://drupal.org/node/23176

Planning the drupal server infrastructure
http://drupal.org/node/26707

Enjoy,

Amnon
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